One (obvious) reason why there are more perfect games
Contrarian reader Andrew Douglas makes the obvious point that there are a lot more Major League Baseball games nowadays than there were in the first six decades of the 20th Century, and they play a slightly longer season. That can account for some—but probably not all—of the recent flurry of these exceptionally rare events that I remarked on yesterday.
From 1901 through 1960, with minor variations, 16 teams played 154 games per season, for a total of 1,232 games per year (16 x 154 ÷ 2).
In 1961, the season was lengthened to 162 games, an increase of about five percent. Baseball added two teams in each of 1961 and 1962, four more in 1969, and two each in 1977, 1993, and 1998.
Since then, 30 teams have played 162 games, for a total of roughly 2,430 per year, or almost twice as many as in the years 1901 to 1960.
Still, from 1901 to 1960, there was only one perfect game every 15 years. From 1980 to last Saturday, there was one every 2.6 years.